Formal flood investigations

The extent to which a particular flood enquiry is investigated is determined on a case-by-case basis considering factors such as the likely source, duration and severity of impact of the flood incident.

As the Lead Local Flood Authority (LLFA) for Derbyshire one of our duties under the Flood and Water Management Act (FWMA) 2010 is to investigate flood events that occur within its area, as it deems necessary.

Section 19 of the FWMA states:

On becoming aware of a flood in its area, a LLFA must, to the extent that it considers it necessary or appropriate, identify:

whether each of those risk management authorities has exercised, or is proposing to exercise, those functions in response to a flood event.

Although the FWMA does not specify that the LLFA must resolve the flooding issue, the conclusion of our investigation's findings will try to identify actions which may reduce the future likelihood of similar events or identify measures to mitigate the impacts. The LLFA must investigate the cause, publish the results of the investigation and notify any of the identified risk management authorities.

In some circumstances a flood enquiry triggers a formal investigation. The trigger for a formal investigation is when the enquiry meets or exceeds locally agreed criteria. Locally agreed criteria was agreed by our Strategic Flood Board.

The thresholds have been subject to consultation and will be reviewed by the Strategic Flood Board when necessary and are:

an event where five or more residential properties, or two or more non-residential (industrial/commercial) have been internally flooded

an event where a flooding problem is recurring and is supported by records or anecdotal evidence as having occurred more than once in a 10 year return period for any given location

an event where threat to life and/or threat of injury or harm has occurred

an event which affects an area or community with a concentration or high proportion of vulnerable people

an event which impacts on critical infrastructure (water, sewage treatment, electricity/gas distribution, telecommunications and the strategic transport network) in excess of 12 hours before restoration of service

an event which impacts on essential services (emergency services, NHS, local or central Government services) in excess of 12 hours before restoration of service.

A formal flood investigation report undertaken by us may include content such as:

all available background information and associated historical flooding data

Private landowners also have responsibilities in relation to land drainage.

Following the conclusion of a formal investigation, a flood investigation report will be completed and published to report the findings of the investigation to the affected community and key stakeholders. An event where the flood is perceived to have a 'known' cause and a risk management authority acknowledges that cause, no formal investigation will be undertaken.